Dart driveshaft

I have one which I believe will fit, but I'd need you to find out what the correct length would be, to verify that it's right. I won't be able to get to it until after New Year's Day but will measure it then. Gentleman who sold it to me said he had an A-body/727/340/8 3/4. Shaft is shorter than my 904/8 3/4 so I'm inclined to believe it's correct. let me know if I can help, and good luck.